Nuclear Posture Review (Excerpts)

February 2, 2018

Weapon Program: 

  • Nuclear

Secretary’s Preface

On January 27, 2017, the President directed the Department of Defense to conduct a new Nuclear Posture Review (NPR) to ensure a safe, secure, and effective nuclear deterrent that protects the homeland, assures allies and above all, deters adversaries. This review comes at a critical moment in our nation’s history, for America confronts an international security situation that is more complex and demanding than any since the end of the Cold War. In this environment, it is not possible to delay modernization of our nuclear forces if we are to preserve a credible nuclear deterrent—ensuring that our diplomats continue to speak from a position of strength on matters of war and peace.


We must look reality in the eye and see the world as it is, not as we wish it to be. This NPR reflects the current, pragmatic assessment of the threats we face and the uncertainties regarding the future security environment. Given the range of potential adversaries, their capabilities and strategic objectives, this review calls foraflexible, tailored nuclear deterrent strategy. This review calls for the diverse set of nuclear capabilities that provides an American President flexibility to tailor the approach to deterring one or more potential adversaries in different circumstances.



Iran, too, poses proliferation threats. Iran’s Supreme Leader, Ayatollah Ali Khamenei, has most recently stated that, “America is the number one enemy of our nation.” While Iran has agreed to constraints on its nuclear program in the Joint Comprehensive Plan of Action (JCPOA), absent extensive international actions many of the agreement’s restrictions on Iran’s nuclear program will end by 2031. In addition, Iran retains the technological capability and much of the capacity necessary to develop a nuclear weapon within one year of a decision to do so. Iran’s development of increasingly long-range ballistic missile capabilities, and its aggressive strategy and activities to destabilize neighboring governments, raises questions about its long-term commitment to foregoing nuclear weapons capability. Were Iran to pursue nuclear weapons after JCPOA restrictions end, pressures on other countries in the region to acquire their own nuclear weapons would increase. 

Nuclear terrorism remains a threat to the United States and to international security and stability. Preventing the illicit acquisition of a nuclear weapon, nuclear materials, or related technology and expertise by a violent extremist organization is a significant U.S. national security priority. The more states--particularly rogue states--that possess nuclear weapons or the materials, technology, and knowledge required to make them, the greater the potential risk of terrorist acquisition. Further, given the nature of terrorist ideologies, we must assume that they would employ a nuclear weapon were they to acquire one.


A Tailored Strategy for Iran

Iran views U.S. influence in the Middle East as the foremost threat to Iran’s goal to establish itself as the dominant regional power. Iran is committed to increasing its influence over neighboring countries and countering U.S. influence. This goal directly threatens U.S. allies and partners, and Iran’s defense policy, strategy, and force structure indicate an attempt to create exploitable military advantages.  

Iran continues to invest in the largest missile program in the Middle East and could, in the future, threaten or deliver nuclear weapons were Iran to acquire them following expiration of the JCPOA, in violation of the NPT and its nuclear non-proliferation obligations. Iran also is developing other non-nuclear military capabilities, including cruise missile systems and cyber warfare capabilities for offensive operations. It may also continue to invest in chemical and biological weapons.

Many of the JCPOA’s key constraints on Iran’s nuclear program end by 2031, shortening the time it would take Iran to produce enough weaponsgrade nuclear material for a nuclear weapon. Iran’s development of increasingly accurate and sophisticated ballistic missiles gives it the capability to threaten U.S. forces, allies, and partners in and outside the region. Were Iran to decide to acquire nuclear weapons, pressures on other countries in the region to acquire their own nuclear weapons would increase.

Our deterrence strategy is designed to ensure that the Iranian leadership understands that any non-nuclear strategic attack against the United States, allies, and partners would be defeated, and that the cost would outweigh any benefits. There is no plausible scenario in which Iran may anticipate benefit from launching a strategic attack. Consequently, U.S deterrence strategy includes the capabilities necessary to defeat Iranian non-nuclear, strategic capabilities, including the U.S. defensive and offensive systems capable of precluding or degrading Tehran’s missile threats. The United States will continue to strengthen these capabilities as necessary to stay ahead of Iranian threats as they grow. Doing so will enhance U.S. security and that of our regional allies and partners.